Deceleration parameter

About: Deceleration parameter is a research topic. Over the lifetime, 1776 publications have been published within this topic receiving 89440 citations.

Aspects of some Rastall cosmologies

Abstract: Rastall gravity paradigm producing mechanism for realizing singular and non-singular cosmologies has been investigated. A solution in Rastall gravity with flat spatial sections which exhibits constant deceleration parameter has been obtained. The study of bouncing scenario in Rastall gravity infers that this scenario may satisfy an affine equation of state during the bounce. Moreover, the physical, kinematic and thermodynamic aspects of the model are discussed in detail. Furthermore, the Raychaudhuri-like equation and other field equations for homogeneous and anisotropic metrics are also derived.

Oscillating Quintom Model with Time Periodic Varying Deceleration Parameter

Abstract: We propose a new law for the deceleration parameter that varies periodically with time. According to the law, we give a model of the oscillating universe with quintom matter in the framework of a 4-dimensional Friedmann—Robertson—Walker background. We find that, in the model, the Hubble parameter oscillates and keeps positive. The universe undergoes decelerating expansion and accelerating expansion alternately without singularity

Bulk viscous embedded hybrid dark energy models

Abstract: In this paper, we have constructed the cosmological model of the universe in a two-fluid environment with a newly developed mathematical formalism. In order to construct the model, Binachi type V (BV) space time is considered with a time varying deceleration parameter. Both the fluids, the viscous fluid and the dark energy (DE) fluid have shown their dominance respectively in early time and late time of the cosmic evolution. The scale factor that simulates the cosmic transition based on the value of the bulk viscous coefficient. Within the developed formalism, a general form of the skewness parameters is also obtained as a functional form of the scale factor. The physical parameter of the model such as equation of state (EoS) parameter is also derived and analysed. The state finder diagnostic pair is also obtained to understand the geometrical nature of the model.

New holographic dark energy model with non-linear interaction

Abstract: In this paper the cosmological evolution of a holographic dark energy model with a non-linear interaction between the dark energy and dark matter components in a FRW type flat universe is analysed. In this context, the deceleration parameter q and the equation state w Λ are obtained. We found that, as the square of the speed of sound remains positive, the model is stable under perturbations since early times; it also shows that the evolution of the matter and dark energy densities are of the same order for a long period of time, avoiding the so-called coincidence problem. We have also made the correspondence of the model with the dark energy densities and pressures for the quintessence and tachyon fields. From this correspondence we have reconstructed the potential of scalar fields and their dynamics.

Bianchi type-I cosmology in $f(R, T)$ gravity

Abstract: We investigate the exact solutions of a Bianchi type-I space-time in the context of f(R, T) gravity [1], where f(R, T) is an arbitrary function of the Ricci scalar R and the trace of the energy-momentum tensor T. For this purpose, we find two exact solutions using the assumption of a constant deceleration parameter and the variation law of the Hubble parameter. The obtained solutions correspond to two different models of the Universe. The physical behavior of these models is also discussed.